The beacon in Dourbes

Characteristics of the beacon

Frequency

49.970 MHz

Power

150 W

Polarization

RHCP

Waveform

cw

The beacon is located on the site of the "Centre de Geophysique du Globe" in Dourbes. Coordinates are: latitude=50,0972° N, longitude=
4,5847° E. The exact location of the beacon is indicated by a red circle on the image below which is an aerial view of the site

During the period [September 2010,September 2011], we used a crossed 2-element Yagi antenna similar to
the one used for the Ieper beacon. The pure sine signal is generated with a PICOTEST G5100-A waveform generator. The signal is amplified with a 400W CW RF amplifier from
Tomco technologies (model BT00400 ALPHA-SA-CW).

Since 30/09/2011, a 8m x 8m metallic grid is used as reflector. Indeed, simulations show that with this device, the power is mainly
emitted upward and the gain is increased by 3.6 dB compared to the Ieper beacon. The figure below shows the theoretical pattern of both
antennas.

Below are some images of the beacon (new antenna, initial antenna, signal generator, power amplifier, 10 MHz reference using a GPS clock):